1. Field of the Invention
The present invention generally relates to a data transmission, and more particularly, to a data receiver and a method for adjusting the data receiver.
2. Description of Related Art
There are several consumer analog standards for transmitting audio/video data, such as coaxial cable, composite video, S-Video, component video, Video Graphics array (VGA), etc. These consumer analog standards are usually used on audio/video devices, e.g. a digital television, or a DVD player. Analog signals need more bandwidths than digital signals for transmitting audio/video data. With audio/video data streams growing fast, these consumer analog standards can not process a large number of audio/video data in time. Therefore, the High-Definition Multimedia Interface (HDMI) is provided to solve the demand.
There is a plurality of differential signals within a HDMI cable, and the differential signals are utilized to transmit audio/video data. A scheme, Serializer/Deserializer (SERDES), is applied to HDMI. The SERDES includes a pair of functional blocks: a serializer and a deserializer. The serializer is a Parallel-to-Serial converter, and is utilized to convert audio/video data from parallel type into serial type. The deserializer is a Serial-to-Parallel converter, and is utilized to convert audio/video data from serial type into parallel type. In other words, the serializer is a transmitter, and the deserializer is a receiver. Therefore, the transmitter of a SERDES converts audio/video data into differential signal, and outputs the differential signal to the receiver of the SERDES. The receiver of the SERDES receives the differential signal and restores the audio/video data.
FIG. 1 is a functional block diagram of a receiver of a SERDES of the prior art. Referring to FIG. 1, the receiver 100 includes an equalizer (EQ) 101, a Clock and Data Recovery (CDR) unit 103, a decoder (DEC) 105. A differential signal has a pair of two signals P and N. The equalizer 101 receives the differential signal, and compensates the differential signal in order to equalize the compensated differential signal and the differential signal outputted from the transmitter. The CDR unit 103 samples the compensated differential signal for generating raw data. The decoder 105 retrieves the audio/video data from the raw data, and outputs the audio/video data to a video processor (VPU) 107.
During the data transmission between the transmitter and receiver of the SERDES, the differential signal may suffer the attenuation due to a long cable, or the differential signal is too strong to criterion of the receiver 100. The equalizer 101 enlarges the weak differential signal or reduces the strong differential signal according to a configuration TEXT provided from outside of the receiver 100. By tuning the configuration TEXT, the equalizer 101 keeps the differential signal to meet the operating boundary of the CDR unit 103. In tradition, tuning the configuration TEXT can be modified manually in manufacture process, or modified by a software in advance. But these methods cannot handle compensation of the equalizer 101 in real time.